Pig rich at wide open throtle (10.9-11.0 air fuel ratio)

[garybohannon]

My friends 1979 Trans Am 403 is rich at wot. The Fast meter shows 10.9-11.00 every time.
The engine has a 224-234 cam and ported heads and headers. AF ratios are 13.2 range at cruise. Idle is rich at 12.5-13.0.
Secondary air valve spring is "a little over half turn".
Au rods (.527 / long tips) and G hanger in secondary.
RobbMc fuel pump with 1/2" lines and pickup.
* My guess is that a metering rod with .30 tip would not cause that high ratio on the fuel.

[garybohannon]

Forgot to mention: Carb is an original 1979 Pontiac q-jet with Cliffs 2nd recipe.

[Cliff Ruggles]

It should be fine with .052" rods in it.  What primary jets and metering rods are being used?

Where is the float level?

Fuel pressure?

Diameter of the fuel inlet seat?.....Cliff

[garybohannon]

*  Fuel system has Robbmc pump, 1/2"fuel line, big filter.
*  n/s is .135"
*  Float is 1/4"
Secondary rods: swapped the .0527 for our new Ruggles custom .062 with G hanger, and got "Fast" meter reading of 12.0-12.2. at full throttle.
Primary jets: swapped .074 jets to .073 and still get 12.0-12.5 at idle, off idle and cruise.
 .....thinking we need to open the bypass a bit larger and lower the apt next. Can't see going to a .072 jet with ethanol-fuel and our 12 degrees initial advance.

[Marx3]

I had a late 70's unit give me rich conditions no matter what I did. Found out the MAB's were too small. I opened up the upper mab's a bit ( can't remember from what size, to what size, but I would think I went up about .010 inches.
That cleared up any rich condition and the afr's were spot on.

What sizes are your MAB's?

[Cliff Ruggles]

Jet size has no effect on idle A/F.

APT is used to change part throttle A/F, and if you can't get it in range change to a different primary metering rod.

The 1979 403 used an Oldsmobile Q-jet, not a Pontiac q-jet, and they are similar but not the same and require a slightly different set-up when tuning them.

It would help to have ALL of the engine specs, and the carb number and exactly what's in it, and what tuning parts are being used, etc.....tks....Cliff